Beyond “Slash and Burn”

Slash and burn. Most of us know this practice is bad news for the environment. Farmers clear land by cutting down all the vegetation (slashing) and then burning away what’s left, releasing carbon dioxide into the air. After a few years, when the soil nutrients are depleted, farmers move on to a new plot of land and leave the old plot to fallow and eventually replenish itself. In Sub-Saharan Africa, slashing and burning and poor soil quality feed into each other, creating an endless loop of land degradation and inefficiency. But what if there were a way to keep farmers from burning up all the biomass left behind by slashing while also enhancing the soil’s retention of nutrients and water?

Biochar—biomass burned without oxygen to form charcoal—has the potential to end the slash-and-burn cycle. Studies have shown that biochar added to soil increases the soil’s ability to retain water and nutrients. But for people to use it, the technology needs to be both effective and affordable. That’s where IFPRI research fellow Alex De Pinto saw an opportunity.

“The biophysical side of this has been explored,” De Pinto said. “Now we need to work out the economic side.”

De Pinto is launching a study of the economic viability of “slash and char” as an alternative to slash and burn, working with partners at Ghana’s Soil Research Institute and Kwame Nkrumah University of Science and Technology, who are running trials on how biochar affects the soil. De Pinto’s research will focus on the costs: clearing the land, transporting the biomass, turning that biomass into biochar, and distributing the biochar to farmers.

Depending on his results, De Pinto sees many possibilities for biochar to improve agriculture in developing countries. Using biochar should lead to richer soil and increased productivity, reducing farmers’ need to clear new land. It could also be linked to cap-and-trade or carbon-
payment schemes, giving farmers not only richer soils and increased yields but also a monetary incentive to capture and use carbon rather than releasing it into the air by simply burning a field.

Could biochar help spell the end of slash and burn? De Pinto is working on the answer.

Although South Asia has the highest concentration of undernutrition in the world, in the past two decades Bangladesh and Nepal have both achieved striking improvements in the nutrition of their citizens. How did they do it?